1. Field of the Invention
This invention relates in general to alignment and centering tools, and, more particularly, to an alignment and centering tool for use in establishing, maintaining and restoring a predetermined fixed geometry between a rotor and a stator.
2. Description of the Related Art
Optical encoders have enjoyed widespread use in a broad variety of applications. However, one of the most important maintenance and installation problems associated with optical encoders is to establish, maintain or restore a predetermined fixed spatial relationship between the encoder rotor and the stator housing of the optical encoder, so that the optical alignment between the spinning encoder disk and the optically active reading circuitry is correct and proper. Whenever the proper alignment between these two mechanically interacting elements is lost, the ability of the optical reading circuitry to correctly interpert the spinning encoded disk is adversely affected, resulting in a consequent failure of the optical encoder to perform optimally its designed function.
Misalignment of the rotor and the stator in an optical encoder is commonplace due to a wide variety of factors, some of which are inherent in the mechanical interaction of a spinning disk and a stationary housing. Some of these factors are tightening screws loosened by mechanical vibration, shock induced stress forces from movement of the optical encoder in shipping, and the general wear and tear occasioned by inertial forces caused by a spinning disk which is subjected to acceleration and deceleration as it controls the movement and positioning of associated elements.
To date the prior art has consisted of requiring maintenance personnel to employ various alignment devices such as lasers, levels and calipers to align a rotor with respect to its stator housing to manufacturer's published tolerances. As a result of using a number of alignment devices, and the varying individual ability of the maintenance personnel, the procedure is both time consuming, costly and is likely to produce non-uniform results.
Thus, during the life cycle of a device having a rotor and a stator, such as an optical encoder having a disc and a photohead, these moving mechanical parts are aligned several times by different people with different skills and with different tools. For example, calibration at the factory usually includes laser positioning of the moving elements; final inspection at the quality assurance section of the factory is usually a visual inspection; incoming inspection at the customer's location is usually another visual inspection; and finally, installation at the customer site generally relies on available equipment and the ability of the installation personnel.
With the present invention, the above alignment procedures are reduced to one manual adjustment at the factory by experienced personnel. Three subsequent adjustments using the tool of the present invention provides for superior reliability over the prior art method and tools.
The present invention provides a single alignment and centering device that quickly and uniformly produces the correct alignment and centering tolerances required by the manufacturer while eliminating errors caused by the complexity of the alignment procedure or the inexperience of the maintenance personnel.